Recently, I was tagged in a comment on a Facebook page for NAR GREEN Designees that posed the question - "Are solar panels less efficient when they are dusty?" Several agents commented without a definitive answer. One agent who is continually searching for correct answers and articles tagged me in that feed.
Being asked questions is a great way to share knowledge, but also to catch up on research. As with any real estate related question, accurate answers backed with research is the only way we should be answering. Energy related information is constantly evolving and staying up on this topic is a constant effort. With real estate being the primary focus for my business, energy efficiency research can sometimes take a backseat. But not today!
As a solar homeowner, I can testify that layers of dust reduce the energy production by solar panels. Before we hit that arena of information, let's talk about how energy is created by solar panels
In order for solar panels to produce power, an inverter is required and connected to the solar array. The sun's rays produce Direct Current (DC) and an inverter switches that power to Alternating Current (AC) so the electricity can be used inside a home. Typically an app is included with solar panels, or the company website, can illustrate the energy produced by day, month and year. Comparing historical and current metrics is the easiest way to know if your energy production is reduced or if other issues exist
Inverters for solar panels can be singular for an entire solar array or micro inverters that are under each panel. The difference is that with one inverter, is that if one solar panel is covered with dust or shaded, the entire solar array is affected and energy production is reduced or eliminated entirely. With micro inverters, a single panel can be affectd versus an entire array. So, if one panel is shaded or covered with dust, only the panel that is shaded or covered is affected.
A similar illustration can be made for snow covered panels. If all of the panels are covered with snow, obviously energy production is reduced if not eliminated. If there is a heavy snowfall, zero energy is produced. If the snow melts and some of the panels are snow free, that panel may produce energy IF the solar array has micro inverters. If there is one inverter for the entire array and one panel is covered with snow, then the entire array is not producing power.
To illustrate the diference in energy production if a solar panel dusty refer to the photos below. The higher number is on a sunny day, while the lower number reflects that the solar panels are dusty. In Phoenix, it is more likely that a layer of dust is covering solar panels versus snow!
The photo below is from the app on my cell phone. I have 14 solar panels and a micro-inverter is underneath each panel. The solar panels were dusty as it hadn't rained much in 2025. Notice the numbers aren't exactly the same.
This second photo is from today, 3/20/25 after it has rained and cleaned the dust from the panels. The solar panels are now producing more power! Why did I not have the solar panels cleaned? Because the reduction in energy production was not enough to warrant spending over $100 to clean them! I might have considered it if it hadn't rained soon though :)
If you have questions or need more information on the least expensive ways to lower your energy bills, make sure to contact the professionals. Realtors that have earned the National Association of REALTORS® GREEN Designation are trained to understand these features and explain how they work!
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